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Physics questions and answers

Physics Questions and Answers

If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.

3,383.

An air bubble of volume 2 cm3 is formed 20m under water. What will be its volume when it rises to just below the surface of the water if the atmospheric pressure is equivalent to a height of 10m of water?

A.

6cm3

B.

4cm3

C.

3cm3

D.

2cm3

E.

1cm3

Correct answer is A

P1V1 = P2V2

When the bubble comes to the surface and pressure drops 3 times, the volume increases 3 times.

V2 = 3 x 2 

= 6 cm3

3,384.

Hot water at a temperature of t is added to twice that amount of water at a temperature of 30°C. If the resulting temperature of the mixture is 50°C. Calculate t.

A.

90oC

B.

80oC

C.

50oC

D.

40oC

E.

30oC.

Correct answer is A

Final Temperature = m1T1+m2T2m1+m2

where m1 and m2 are the weights of the water in the first and second containers.

T1 and T2 are the temperatures of the water in the first and second container.

Given Final temperature = 50°C;

Let m1 = b, then m2 = 2b.

T1 = t; T2 = 30°C

50 = \frac{bt + 2b(30)}{3b}

50(3b) = bt + 2b(30) \implies 150b = b(t + 60)

150 = t + 60 \implies t = 150 - 60 = 90°C